Device and method for diagnosing switch using voltage distribution

Abstract

The present invention relates to a device and a method for diagnosing a switch using voltage distribution, and more particularly, to a device and a method for diagnosing a switch using voltage distribution, which connect one or more resistors connected in series with the switch in parallel and calculate voltage applied to one resistor among one or more resistors by using the voltage distribution to diagnose a state of the switch based on the calculated voltage, in order to diagnose the state of the switch positioned on a cathode power supply line connecting a battery and a load.

The invention claimed is: 
     
       1. A device for diagnosing a cathode switch positioned on a cathode power supply line adapted to switch between connecting and disconnecting a battery and a load, the device comprising:
 a reference voltage circuit connecting a first point on the cathode power supply line between the battery and the cathode switch to an anode power supply line between the battery and the load, the reference voltage circuit including at least one first resistor and a first switch; 
 a cathode switch diagnosis circuit connecting a second point on the cathode power supply line between the cathode switch and the load to the anode power supply line between the battery and the load, the cathode switch diagnosis circuit including at least one second resistor and a second switch; and 
 a controller configured to:
 measure a reference voltage at a cathode power supply line side of the first resistor; 
 measure a diagnosis voltage at the cathode power supply line side of the second resistor; and 
 diagnose a state of the cathode switch based on a comparison of the measured reference voltage to the measured diagnosis voltage. 
 
 
     
     
       2. The device of  claim 1 , further comprising:
 an ADC conversion unit converting the reference voltage into a first digital signal, and the diagnosis voltage into a second digital signal 
 wherein the controller is configured to diagnose the state of the cathode switch based on a comparison of the first digital signal to the second digital signal. 
 
     
     
       3. The device of  claim 1 ,
 wherein the cathode switch diagnosis circuit includes a plurality of second resistors, 
 wherein the second switch is positioned between the plurality of second resistors, and 
 wherein the controller is configured to:
 control the second switch to a closed state; and 
 measure the diagnosis voltage while the second switch is in the closed state. 
 
 
     
     
       4. The device of  claim 1 ,
 wherein the cathode switch diagnosis circuit includes a correction voltage generator configured to apply a correction voltage to the second resistor, 
 wherein the controller is configured to:
 sum the diagnosis voltage and the correction voltage; and 
 diagnose the state of the cathode switch based on the summed voltage. 
 
 
     
     
       5. The device of  claim 1 , further comprising:
 an anode switch positioned on the anode power supply line and adapted to switch between connecting and disconnecting the battery and the load; 
 a diagnostic resistor for diagnosing the anode switch; and 
 an anode switch diagnosis circuit of which a first side is connected with the anode switch and a second side is connected with the diagnostic resistor. 
 
     
     
       6. The device of  claim 5 , wherein the controller is configured to:
 calculate a voltage applied to the diagnostic resistor from a voltage of the battery applied to the anode switch diagnosis circuit and the diagnostic resistor based on voltage distribution; and 
 diagnose a state of the anode switch based on the calculated voltage. 
 
     
     
       7. The device of  claim 1 , wherein the cathode switch and the switch constitute a cathode switch diagnosing unit and the controller is positioned outside of the cathode switch diagnosing unit. 
     
     
       8. A method for diagnosing a cathode switch positioned on a cathode power supply line adapted to switch between connecting and disconnecting a battery and a load, the method comprising:
 measuring, by a controller, a refernece voltage at a reference voltage circuit connecting a first point on the cathode power supply line between the battery and the cathode switch to an anode power supply line between the battery and the load, wherein the reference voltage circuit includes at least one first resistor and a first switch and wherein the reference voltage is measured at a cathode power supply line side of the first resistor; 
 measuring, by the controller, a diagnosis voltage at a cathode switch diagnosis circuit connecting a second point on the cathode power supply line between the cathode switch and the load to the anode power supply line between the battery and the load, wherein the cathode switch diagnosis circuit includes at least one second resistor and a second switch, and wherein the diagnosis voltage is measured at the cathode power supply line side of the second resistor; and 
 diagnosing, by the controller, a state of the cathode switch based on a comparison of the measured reference voltage to the measured diagnosis voltage. 
 
     
     
       9. The method of  claim 8 , further comprising:
 converting, by an ADC conversion unit, the refernece voltage into a first digital signal, and the diagnosis voltage into a second digital signal, 
 wherein diagnosing the state of the cathode switch is based on a comparison of the first digital signal to the second digital signal. 
 
     
     
       10. The method of  claim 8 , wherein the cathode switch diagnosis circuit includes a plurality of second resistors, wherein the second switch is positioned between the plurality of second resistors, the method further comprising:
 controlling the second switch to a closed state; and 
 measuring the diagnosis voltage while the second switch is in the closed state. 
 
     
     
       11. The method of  claim 8 ,
 wherein the cathode switch diagnosis circuit includes a correction voltage generator configured to apply a correction voltage to the second resistor, 
 wherein the method further comprises summing the diagnosis voltage and the correction voltage, and 
 wherein diagnosing the state of the cathode switch is based on the summed voltage. 
 
     
     
       12. The method of  claim 8 ,
 wherein an anode switch is positioned on the anode power supply line and is adapted to switch between connecting and disconnecting the battery and the load, wherein an anode switch diagnosis circuit is connected at a first side with the anode switch and with a diagnostic resistor at a second, the method further comprising diagnosing, by the diagnostic resistor, the anode switch. 
 
     
     
       13. The method of  claim 12 , the method further comprises calculating, by the controller, a voltage applied to the diagnostic resistor from a voltage of the battery applied to the anode switch diagnosis circuit and the diagnostic resistor based on voltage distribution, and wherein diagnosing the anode switch comprises diagnosing a state of the anode switch based on the calculated voltage. 
     
     
       14. A method for installing a cathode switch diagnosis circuit for diagnosing a cathode switch positioned on a cathode power supply line adapted to switch between connecting and disconnecting a battery and a load, the method comprising:
 connecting a reference voltage circuit between (i) a first point on the cathode power supply line between the battery and the cathode switch and (ii) an anode power supply line between the battery and the load, wherein the reference voltage circuit includes at least one first resistor and a first switch; 
 connecting the cathode switch diagnosis circuit between (i) a second point on the cathode power supply line between the cathode switch and the load and (ii) the anode power supply line between the battery and the load, wherein the cathode switch diagnosis circuit includes at least one second resistor and a second switch; and 
 positioning a controller to receive a measurement of a reference voltage at a cathode power supply line side of the first resistor and diagnosis voltage at the cathode power supply line side of the second resistor. 
 
     
     
       15. The method of  claim 14 ,
 wherein the cathode switch diagnosis circuit includes the cathode switch; and 
 wherein the controller is positioned outside the cathode switch diagnosis circuit.